Radiation

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silmag
WUFI User
WUFI User
Posts: 13
Joined: Wed Apr 12, 2017 5:56 am -1100

Radiation

Post by silmag » Mon Mar 18, 2019 5:47 am -1100

Hello,

I was testing WUFI Plus with some External Climatic Files (we bought to the Portuguese Meteorological entity) and I found that "Global Radiation" does not have an influence on the internal climate simulated (with or without that column, the results of internal climate are the same). On the other hand, "Direct Radiation" and "Diffuse Radiation" plays an important role once the results are much different considering it or not.

So, i would like to understand which Radiation Parameters are the most important, considering i want to simulate the internal climate of my building (and not the component itself), and which Radiation parameters are not that important (Maybe the "Counterrad" radiation for instance, or the "Global Radiation Horizontal" once it has no influence in my test model).

Another question is: if we don't insert any Radiation in the External Climatic File, does Wufi considers any default value? Once in "Location/Climate / Analyse" i can see a "Counterradiation Sum" Value, even when i didnt insert any Radiation Column....
And how it distributes by different orientations?

On WUFI Wiki it refers:
"The radiation rose shows the yearly sum of global radiation for receiving surfaces with different orientations and inclinations"

Does wufi considers any default value and any distribution by Orientation?

Thank you very much in advance.
Sílvia Magalhães
Sílvia Magalhães
FEUP, Oporto

mpazold
WUFI SupportTeam IBP
WUFI SupportTeam IBP
Posts: 183
Joined: Wed Jul 11, 2012 11:21 pm -1100

Re: Radiation

Post by mpazold » Wed Apr 17, 2019 11:21 pm -1100

Hello,

The global radiation is the diffuse + direct horizontal radiation. In your case, if you have the direct and the diffuse radiation the global radiation is not necessary and not used. 2 of the 3 (global, direct, and diffuse) should be in the climate data.
The counterradiation, if it is not in the climate data, can be estimated by air temperaure, relative humidity of the air and a cloud factor.

Isolar radiation is NOT calculated per default, if ther is no data in the climate file, no radiatio is considered. For this i recommend not use the explizit radiation balance using the counterradiation.

WUFI calculate the direct radiation epending on orientation and inclination for each surface. (The direct radiation in the climate file should be the direct horizontal radiation). If shading is checked, it also calculates direct shading of visualized components. The diffuse radiation is also calculated depending on the hemispherical view factor.

more detailed information:
https://wufi.de/en/service/downloads/cr ... her-files/

best regards,
Matthias

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